It has become increasingly common for soft drinks and other beverages to be sold in bottles made of plastic. Bottles made of the plastic polyethylene terephthalate (PET) have become particularly popular with the soft-drink industry because of their transparency, light weight and low cost. Typically, such bottles are of a one-liter, two-liter, three-liter, or four-liter capacity.
Two types of PET bottles are generally used by soft drink bottlers today: a base-cup type and a petaloid type. Both types of PET bottles are generally symmetric in shape having a longitudinal symmetry axis.
Conventional PET bottles of the base-cup type have three parts: a vessel made of PET plastic for containing the beverage, a closure for sealing the vessel, and a base cup. The base portion of the PET vessel is generally hemispherical in shape and thus does not provide a surface on which the bottle can stand upright. The base cup is a separately formed piece which is attached to the base of the PET vessel and has a bottom which is shaped to permit the bottle to stand upright on a flat horizontal surface.
Conventional PET bottles of the petaloid type have only two parts: a petaloid vessel made of PET plastic and a closure for sealing the vessel. Typically, the base portion of the PET petaloid vessel has six petaloid lobes projecting from it in a generally circular arrangement. Bottom surfaces of the lobes are generally substantially coplanar with respect to one another and permit the bottle to stand upright on a horizontal flat surface.
Although the walls of PET bottles are flexible, they are strong in tension and thus can safely contain the pressure of carbonated beverages. Moreover, conventional PET bottles of either the base-cup or the petaloid type can bear surprisingly high compressive loads if the load is directed substantially along the longitudinal symmetry axis of the bottle. A single PET bottle can support the weight of many bottles of the same size filled with beverage if the bottle in question is standing upright and the weight of the other bottles is applied to the closure of the single bottle and directed substantially vertically along the symmetry axis. However, if a compressive load is applied to a conventional PET bottle along a direction other than the symmetry axis of the bottle, the bottle tends to buckle and give way.
U.S. Pat. No. 4,344,530 of deLarosiere (the '530 patent) discloses a molded plastic case for PET bottles. The case has bottle pockets which are shaped to fit closely the bases of bottles inserted in the pockets and so to orient the bottles along the centerlines of the pockets. Thus, bottles seated in the pockets are oriented so that the weight of a stack of cases of bottles filled with beverage is properly transmitted along the longitudinal symmetry axes of the bottles. The '530 patent refers specifically only to PET bottles of the base-cup type, although teachings of the patent are applicable to PET bottles of the petaloid type as well. The specific cases exemplified in the '530 patent are only suitable for transporting PET bottles of the base-cup type.
A commercial soft-drink bottling operation typically requires a "float" of tens of thousands of cases to warehouse PET bottles of soft drinks and to deliver the bottles to retail stores. A need exists for a reusable case which permits stable stacking of the cases of PET bottles of both the base-cup type and the petaloid type, so that a soft-drink bottler can switch from one type of PET bottle to the other as market conditions dictate without having to replace the float of cases used to warehouse and deliver the bottles.